[Campbell Biology P.827] Based on Figure 35.30 and the associated text, what would be the li... | Practice Question

Based on Figure 35.30 and the associated text, what would be the likely effect on root hair development if the GLABRA-2 gene were rendered completely dysfunctional by a mutation?

  • A: All epidermal cells in the root would develop root hairs.
  • B: No epidermal cells in the root would develop root hairs.
  • C: Root hair development would be unaffected, as GLABRA-2 only influences the root cap.
  • D: Only epidermal cells bordering a single cortical cell would develop root hairs.

Explanation

The passage states that 'The GLABRA-2 gene is normally expressed only in epidermal cells that will not develop root hairs.' It also mentions, 'When an epidermal cell borders a single cortical cell, the homeotic gene GLABRA-2 is expressed, and the cell remains hairless.' Conversely, 'Here an epidermal cell borders two cortical cells. GLABRA-2 is not expressed, and the cell will develop a root hair.' If GLABRA-2 is dysfunctional, it would no longer suppress root hair development, leading to all epidermal cells developing root hairs, regardless of their position.